''Rhinosteus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of small to medium selenosteid

arthrodire Arthrodira (Greek for "jointed neck") is an Order (biology), order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetratin ...

placoderm Placoderms (from Ancient Greek πλάξ 'plax'', ''plakos'''Plate (animal anatomy), plate' and δέρμα 'derma'''skin') are vertebrate animals of the class (biology), class Placodermi, an extinct group of prehistoric fish known from Pal ...

s of the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...

known from the Upper

Frasnian The Frasnian is one of two faunal stages in the Late Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Givetian Stage and followed by the Famennian Stage. Major reef-building was under way during ...

Kellwasserkalk

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with distinctive characteristics. The characteristics can be any observable attribute of rocks (such as their overall appearance, composition, or con ...

Bad Wildungen Bad Wildungen () is a state-run spa and a small town in Waldeck-Frankenberg district in Hesse, Germany. It is located on the German Timber-Frame Road. Geography Location Bad Wildungen lies in the eastern foothills of the Kellerwald range in the ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

and

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

Description

''Rhinosteus'' is a typical genus of Kellwasserkalk selenosteids, with short cheeks, and slender inferognathal (lower jaw) plates. However, two of the species, ''R. traquairi'' and ''R. tuberculatus'', have long, pointed

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

s, and

tubercles In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projection, b ...

on the plates. In ''R. traquairi'', the rostrum is sharply pointed, extending beyond the snout, and the tubercles are small and irregularly placed. In ''R. tuberculatus'', the rostrum is bluntly pointed, and the tubercles are large and plentiful. The species ''R. parvulus'' has a blunt rostrum that does not extend beyond the snout, and lacks tuberculation altogether. The average skull length of ''R. traquairi'' is about 11 centimetres. The average skull length of ''R. tuberculatus'' is 15 centimetres, while that of ''R. parvulus'' is 4 to 6 centimetres.

Distribution

Fossils of ''R. traquairi'' and ''R. tuberculatus'' are found only in

. ''R. parvulus'' is also found in Bad Wildungen. Rücklin (2011) discusses how specimens of small ''Rhinosteus'' have been found in the Kellwasserkalk

of the Anti-Atlas Mountains of

, and are tentatively referred to ''R. parvulus'' due primarily to their small size.

Phylogeny

''Rhinosteus'' is a member of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Selenosteidae Selenosteidae is an extinct family of small to large-sized arthrodire placoderms from the Late Devonian. With the exception of the Chinese '' Phymosteus'', selenosteids lived in shallow seas in what is now Eastern North America (the Cleveland S ...

of the

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Aspinothoracidi Aspinothoracidi is a clade of placoderms, extinct armored fish most diverse during the Devonian. The gigantic apex predator ''Dinichthys'', is the best-known member of this group. Many other genera, such as the infamous ''Dunkleosteus'', were pre ...

, which belongs to the clade

Pachyosteomorphi Pachyosteomorphi is an extinct clade of arthrodire placoderms within the Eubrachythoraci (of the suborder Brachythoraci), armored fish most diverse during the Devonian. Most are considered to be pelagic (open ocean) long-distance swimmers, leadi ...

, one of the two major clades within

Eubrachythoraci Eubrachythoraci is an extinct clade of arthrodire placoderms within the suborder Brachythoraci, armored fish most diverse during the Devonian. Most are considered to be pelagic (open ocean) long-distance swimmers, leading to their widespread dis ...

. The

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below shows the

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

of ''Rhinosteus'':

References

Selenosteidae Placoderms of Europe Placoderms of Africa Arthrodire genera {{Placoderm-stub